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bhupesh (757)

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Olaaa!! Perrrfect answer. 123  [194 rates]

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Dear
  we can apply conservation of energy
1/2 m v^2 + 1/2 mR^2 ( omega ) ^2 + mgr + 1/2 m ( v - omega R )^2  = 1/2 m v' ^ 2 + 1/2 m R^2 ( omega ' ) ^2+ mgR + 1/2 m ( v' ^2 + omega R )^2 + mg2R

where
v = velocity when the small mass is at lowest position
v'= Velocoty when the small mass is at highest position
omega = angular speed when the small is at the lowest position
omega ' = angular speed when the small is at the highest  postion

as the ring is rolling
 
 v = omega R
v'  = omega ' R


Substituting

V ^ 2 =  3 v' ^2 + 2 g R


the catch of the question is The with the small mass is an inhomogeneous body The CG of the system is at a distance of R/2 Above the centre . It acceleration = omega' ^2  X R/2  ( down ward )



a = omega ' ^2 x R/2  = v' ^2 /2 R

Considering the down ward motion of the CG

2mg - N' = mv'^2/R

The ring will not bounce if N' > equal to 0



Solving all the equations v = sqrt 8gR

Bhupesh.M
 this reply: 10 points  (with Olaaa!! Perrrfect answer.   in 2 votes )   [?]
 
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